What does permanent waving solution do to the hair?
- Breaks disulfide bonds by a reduction reaction
- Rebuilds disulfide bonds by an oxidation reaction
- Coats the cuticle with a conditioning polymer
- Breaks peptide bonds by a hydrolysis reaction
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A. Breaks disulfide bonds by a reduction reaction
Waving solution is a reducing agent: it adds hydrogen to the disulfide bonds and breaks them so the hair can take the shape of the rod. Rebuilding the bonds by oxidation is the job of the neutralizer.
Reference: Permanent waving: reduction reaction
Which layer of the hair gives it most of its strength, elasticity and natural color?
- Cuticle
- Dermal papilla
- Medulla
- Cortex
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D. Cortex
The cortex is the fibrous middle layer; it holds the melanin and accounts for most of the hair's weight, strength and elasticity. The cuticle protects the cortex but contributes little strength and holds no pigment.
Reference: Hair science: layers of the hair shaft
Which color neutralizes unwanted orange (brassy) tones?
- Blue
- Violet
- Red
- Green
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A. Blue
Complementary colors sit opposite each other on the color wheel and neutralize one another; blue is opposite orange. Violet is the complement of yellow, so it corrects yellow rather than orange.
Reference: Haircolor: complementary colors
Cutting hair at 0 degrees elevation produces what result?
- Uniform layers with the same length throughout the head
- Long layers with the shortest hair at the top of the head
- A one-length (blunt) cut with weight at the perimeter
- A stacked shape with weight removed from the perimeter
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C. A one-length (blunt) cut with weight at the perimeter
With no elevation all the hair falls to one line, so the weight builds at the perimeter and no layers form. Uniform layers require the hair to be lifted to 90 degrees.
Reference: Haircutting: elevation and basic cuts
Why must implements be cleaned before they are placed in disinfectant?
- Cleaning makes the disinfectant evaporate more slowly during use
- Soap residue is needed to activate the disinfectant solution
- Cleaning alone already destroys bacterial spores on the tool
- Debris left on the surface can stop the disinfectant working
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D. Debris left on the surface can stop the disinfectant working
Hair, skin, oil and product residue shield microbes and can inactivate or dilute the disinfectant, so the surface must be cleaned first. Cleaning does not destroy spores, and soap residue does not activate disinfectant; it should be rinsed off.
Reference: Infection control: cleaning before disinfecting